Fluorescent tube



Aug. 10 1926.

M. SCHMIERER FLUoREscENT TUBE Filed Feb. 27', 1914 4 Sheets-Sheet 4 Jn Ven for:

`mfnesse5z Patented Aug. l0, 1926.

UNITED sTATEs .PATENT oEFlcE.

MICHEL SCHMIERER,

FLUoBEscENT TUBE.

or BERLIN, GERMANY.

HEISSUED.

"Application illedlebruary 2?, 1914, Serial No. 821.609. and in Germany March 5. 1913.

This invent-ion relates to gaseous conduction devices, and is directed, more particularly, to so-jcalled .fluorescent-'tubes or glow lamps. More espec-ially'it relates to glow lamps intended for thev purpose of transmitting pictures by electricity,but may also be used for other purposes,` for, example, for indicating the` direction ot a current iu .Rntgen ray plants, for. advertising purposes and the like. u

All arrangements for transmitting pictures over great distances 1re based onthe principle, that. the picture to be transmitted at the transmitting station is divideilinto luminous points, the intensities ot which are converted into changes in an electric current and are transmitted either simultaneouslv or successively (by means of alternating currents of different frequency). while at the receiving station the reverse process occurs. the incoming current impulses being reeonverted into luminous points ot corresponding intensity, which are then assembled to form a picture.` At the receiving station there must therefore be au arrangement which allows of converting changes in an electric current into changes iu the intensity of light. Of the devices which have been suggested `for this purpose. electric fluorescent tubes afford the advantages of consuming lvery little energy. ot the. color of ,thev light radiated being unchangeable and. above all, of the absolute absence ot inertia. Furthermore they require little space, are proof against vibrations and may be produced at a moderate cost.A Hitherto they were only employed in form of so called Geisslertubes. namely tubes which have been evacuated to a comparatively high degree. the whole spacein which will fiuoresce when a current passes between the electrodes. These Geissler tubes have only a small intensity, so that it requires a comparatively long exposure to suiticientl)7 affeet the sensitive emulsion. A further disadvantage of the Geissler tubes is this, thata picture which has been received by their aid is composed of light and dark superficial elements. Such a picture cannot however. like a photograph, be directly reproduced by any printing method. end would first have to be divided by a line screen by copying it through such onto a zinc plate covered with'chromo-gelatine, so as to produce a Yprinting block-which may be used after the known halic tone method. A half tone picture consists, as generally known. of large. and small points scattered in a chess- `hoard manner over the surface of the picJ turc By the diterent size of these points the various shades are produced. The larger the points at one part of the picture, the

darker this part will appear. it the picture printed. So for instance a screen ruled at' 2 lines per millimeter. thus containing 4 points per square millimeter is used for common newspaper. If likewise 4 points per superficial element of the picture to be transmitted are considered as suiiicient, the superficial element would be 1 square millimeter. It would be impossible to reproduce finer details of a picture.v lt therefore: appears advisable to produ-ce the pictures transmitted direc-tlv in a'half tone manner, so that they may be copied on to the zinc plate without need of a screen. Forthis purpose the device which converts the currentehanges into light changes niust pro duce not only light spots et even size and different intensity but also different size aS well 'lhisobject is obtained by means vof the fluorescent tube hereinafter described, which also meets thev second requirement, namely1 of producing a mere intense lightJV than a common Geissler tube. The size of the. luminous spots produced by this tube, on a current passing through it.. is in direct proportion tothe iutenstv of the current.

ln the 'accompanying drawings:

Fig; 1 is a front elevation of the tube.

Fig. 2 is a horizontal section. Figs. 3 and4 show a combination of plurality of tubes to a panel'of tubes, Fig. 3 beingV an elevation, Fig. 4 a horizontal section.

Figs. 5 to 7 exemplify a few applications, l

namely Fig. 5 a direct connection, Fig. 6 an fluorescence tube'at the receiver, and Fig. i' the indirect connection with a plurality of selenium cells and fiuorescence tubes rc- V spectively.

holes of even diameter at an even and as cases, be made the cathode.

small as possible pitch into a metal plate. The hexagonal shape of theV plate shown in the drawing allows of a good utilization of the space with comparatively large strength and comparatively easy working. Any other arrangement of the holes with the same size and number of holes per superficial unit, would result in a smaller thickness of the webs between the'individual holes and thus render the making of the electrode more difficult. Otherwise Jthe arrangement of the holes is immaterial with regard to the subdivision of the picture to be transmitted into superlicial elements.

The electrode Which is likewise prefer:

ably made of aluminum, is much smaller than the electrode a, and, seen from the observer, `t is arranged behind the same.

The tube is filled with an inert gas, preferably nitrogen and evacuated until the gas pressure amounts to only a few millimeters mercury column. If one of the rare gases, such as helium or neon is used for filling the tube, the current consumption will be considerably lower. The radiated light is, however, poor in actinic rays, so that no material advantage would be 'derivedtherefrom if t e tube is to be usedfor tele-photograpI ic purposes. For tele-optical purposes, luminous advertising signs and the like such a filling would, however, be of advantage. When a. current is sent through the tube the two electrodes will luminesce, the electrode connected to the negative pole of the source of current being of the higher intensity. The luminosity7 at the positive pole is practically negligible. For this reason the luminous electrode a should, in most The radiated light in this/,case will consist of a rather this will clearly defined, almost circular illuminated spotif the anode b is a rotation body, the xis of whichis vertical tolthe planebf the cathode, thus, for example disc, ball, cylinder, cone, 'truncated cone or the like. The spherical shape indicated in the' drawing has the advantage that in case the stem of the electrode should befused in obliquely not aeot the effectiveness of the square and large a polygonal luminous spot instead of a round one.vl lVhen.atfour-cornered electrode b 1s used, especially a -four point star, there will be produced at low current an almost `circular luminous spot, at medium current an almostsquare luminous spot, and at a high current a star shaped luminous spot will be obtained'f4 This fully corresponds with the conditions of a half tone, in which small points are ,.round, medium points points starshaped. If the electrode b,lastly, has on the side turned towards 'fthe electrode a several projecting parts, or if there are several electrodes b conductively connected with each other, as many luminous spots will, on the passage of a current be produced, as there are projecting partis or electrodes The outlines of the individual luminous spots will then, of course,'correspond to the shape of the elec trode Theluse of such subdivided electrodes b is then preferable, when the picture received shall be of a finer ruling than the picture transmitted.

The] area of the luminous spot, or the total area of the luminous spots is almost directly proportional to the intensity of the current. The intensity of the lightlikewise increases with the intensity of the current. The radiation is the most intense within the holes in electrode a. If the radiation is to be limited to the face of the electrode and the space in the holes, the electrode may, ou its yreverse side, be covered with an insulating material, for example a coat of varnish.

The luminous intensity of the fluorescenttube increases with the decreasing of the sectional area of the holes. It is, therefore, in most instances preferable to make the size 0f the holes as small as possible, as the kind and the pressure of the gas allows. The higher the gas pressure, the smaller the size of the hole may be, as the thickness of the dark layer covering the cathode, which is necessary for producing the fluorescence decreas with the gas pressure. As the gas pressure in tubes in use decreases in time,`

The luminosity ofthe tube is further n proportion to the thickness of the electrode plates, or tov the thickness of the electrode a respectively. The best results are obtained with electrodes, which are made of 3 millimeter plate.

` For the purposes of the slower tele-photography for instance by aid of such processes in which one single selenium cell is used in the transmitter for converting the intelisity of the individual elements of the picture into corresponding currrent changes, preterably also one single fluorescent tube is used in the receiver for re-converting the current changes into corresponding light changes. In doing so an arrangement must be made, by which the rays of light radiating from the tube Will strike only such. part of the sensitive film, which corresponds to the rc.- spective acting part of the picture being transmitted. 'This may be effected, by the tube being passed in a zig-zag line or a spiral line in front of the sensitive film, or in a helical line around the same, when the latter is Wrapped on a drum. Vice versa the tube may also be stationary, and the sensitive film will receive a corresponding movement. Also both tube and film may be stationary and the rays emanating from the tube may be directed by suitable optical means, such as a revolving or an oscillating mirror to the. part of the sensitive filmvcorrespondin'g to the respective acting part of the picture being transmitted. Or the rays may be allowed to pass through 'correspondingly shaped' hole or slit shutters onto such parts only. It may also be possible to combine any or several of these methods.l

For `tele-,visual lpurposes and for rapid tele-photography, for instance such methods, in which a-plurality of selenium cells are employed lin the transmitter, also these tubes are preferably employed in a larger number. With a method, in which the several cells are arranged on a panel in such a manner, that they preferably form parallel lines .at right. angles'to each other and at-an even pitch. thev tubes are `preferably arranged in the receiver of the same number and according to the same plan. Then one selenium cell and one fiuorescent tube each Willcorrespond to each luminous point of the picture.V These may either by aid of alternating currents of different frequency transmit the intensities of the individual luminous points simultaneously, or they may be successively connected by means of synchronous commutators into the same circuit. VThe stronger the selenium cell is lighted, the' brighter thus the luminous point, the larger and brighter will be the lighted spot on the plate a of the corresponding fiuorescent tube, so that the panel of fluorescent tubes reproduces the icture transmitted With its accurate gradatlons of light. Such a panel of fluorescent' tubes maybe greatly 'pitch` one 'for each kluminous point.

simplified in its arrangement. by combining according to Fig. 3 (elevation) and Fig. 4 (horizontal section) the tubes of each row .with each other to a multiple tube l. iu

Awhich thc electrodes rz are fused to one single strip-shalied electrode behind which the other pole electrodes B are arranged at even Ot' course also hert` subdivided electrodes B may be employedif.ivhen the received picture shall have a finer ruling than the picture transmitted. .lt is rather immaterial as regai-ds the operation ot the tube, which shape and arrangement. of the holes in the electrode-A are employed, and here the saine remarks apply as `to the single electrode a, of the single tube. .l'fthe electrodes A are made of one single strip of sheet metal, the .same may be continuousliv perforated as thisl is indicated in the uppermost. electrode in Fig. 3. or. a star of holes may be provided for each of the electrodes B, as it is shown in the second electrode A. The commutation of such a tube panel may vbe performed in either of tivo ways. Either, all electrodes A are connected parallel and the electrodes B are connected singly with the sections oi a commutator, in which case a luminous spot is produce-l at that partv of the panel only, which eorrsponds to the electrode B which, for the moment is connectedv through the commutator; or, the Wires leading from each row of electrodes B, 'at right angles to theI electrodes A. are connected with Wires 5 (Figs. 3 and 4) and the electrodes A and the rows vof electrodes B are commutated separately. In this latter'case a luminous spot is produced onlyk at such point Where the connected electrode A crosses the rovv of electrodes B connected. This method of `commutation is illustrated in Fig. 7. Prefplification, all electrodes Amay be fused to one large plate, or, the electrodes B may be conductively connected With each other in,y rows, whereby fused joints-may be saved. In the latter case the saving in fused joints will be greater, but in the former ycase the advantage is derived, that luminous spots may be produced. the diameter of which is 'larger than the distance between the electrodes B, whereby a larger richness in c ontrasts of the picture received may be obtained. The glass'yvall closing-the receiving vessel at lthe front, must be convex, so as to be able to bear the pressure of theatmosphere.

lll)

A panel of fluorescent tubes may, of course also be employed With such plants for picture telegraphy, in which there is only one single photo-electric element (selenium cell or the-like) in the transmitter. Vice versa it is also possible to employ with a plant comprising a plurality of photo-electric elements, at the receiving station only one single tube or a small number of tribes. ln' particular it is possible both with the method employing one single selenium cell, and With that'employing a plurality of selenium cells to use a multiple tube, ifthe luminous rays emanating from the latter are given, relatively to the sensitive film such a movment, that gradually the Whole surface of such film is covered, as thishas been described with reference to the single tube. Generally it is, however', preferable, to employ the same principle at both stations, thus the same number of tubes, -or electrodes B, as there are sensitive to light elements. This affords the advantage` that the Whole plant is simpler and that the same driving mechanism may be used for both stations.

For `feeding such fluorescent tubes a -current of a 'few hundred volts only is suffi- -cient. The intensity of the current is extremely small` so that it is possible to connect them directly in series with the light sensitive element or elements of the transmitter. This connection is diagrammatically exemplified in Fig. 5 for a plant in which at the transmitter the picture tolie transmitted is Wrapped in form of a film on a revolving and axially advancing' glass drum T, While at the receiver the sensitive film is likewise wrapped on a drum T. which has a"synchronous movement. In such arrangements generally one single photo-electric element is employed in the transmitter and one .single lin'ht regulating element at the receiver'. Tn Fig. 5 0 is the lens through which the light of the lamp L is concentrated in one point on the surface of the picture to be transmitted` whereupon, after it has been reduced accordingT to the intensity of this point. it falls onto the selenium cell S. Sometimes With such arrangments the conversion of the intensities into current fluctuations is also obtainedl bv the picture to'be transmitted being applied to the drum. not in form of a film but of a chromo-gelatine plate or also a half tone on a metallic foil, and a feeler which successively covers the Whole surface sends either directly by electric means (under utilization of the variable conductivity of the chromo-gelatine film) or by mechanical means (under utilization of the different heights of the film) currents cor'- respondina' to the intensities into the transmission line. The receiving arrangement remains, however, the same. E is the source of current. At the receiver O is the" lens,

which produces the image of the luminousl spot produced on the electrode a on the sensitive film, which .is laid around the drum T. lt is, however, for practical use, not advisable to connect the fluorescent tube4 directly into the transmission line. It would have the disadvantage that the ,transmitter would be greatly endangered by a possible' short-circuit in the transmission line. Furthermore such direct connection has the disadvantage, that the fluc- K tuation of the total resistance in the circuit, thus also the changes in the intensity of the current are not proportional to the changes in the resistance of`the photo-electric element. as the invariable resistance in the transmission line and the not greatly varying` resistance of the fluorescent tube adds to the resistance of the light sensitive element. For this reason an indirect. connection isyto be preferred, in which the current is transformed toa higher voltage. Fig. 6

illustrates such connection for the receiverv of a plant, the transmitter of which corre- `sponds to Fig. 5. U 1s the interruptor, which 1s used to convert the transmitter current into an intermittent direct current,`

as the direct current derived from the battery B cannot be transformed. The interruptor might also be arranged at the transmitter station. lf, instead of the battery ll a source of alernating current is employed the interruptor is not necessary. t is the transformer.' 'Also this transformer may be arranged at the transmitter. This affords besides a low Ivoltage at the terminals of the photo-electric element, the'further advantage, that the fluctuations of thecurrent in the transn'iissiovn line, thus also in the fluorescent tube are almost proportional to the changes in the resistance of the photo-electric element, as the resistance in the primaiywinding of the transformer is very low compared to the resistance of the transmitter, while the resistance in the transmision line'is considerably greater. It is the best, to employ a double transformation, and to provide a transformer both at the receiving andv at the transmitting stations. This affords the further advantage of a low voltage in the transmission line.

For increasing the transmission speed a larger number of selenium cells v'may be employed ,with the arrangement shown in Figures 5 and 6, these cells being successively connected into the circuit. For reason of a Ygreater simplicity as many fluorescent tubes may be provided in the receiver. VIf the selenium cells are arranged in such a manner, that they are influenced by luminous points axially adjoining each other, in Which case the axial travelv of the drums must be accordingly faster, it is possible to employ in the receiver instead of'sever'al tubes' 4one single multiple tubel of the kind shown in Figs. 3 and 4, one single lens O reproducing all luminous points as luminous points lying axially next to each other on the photosensitive film.

Also when the selenium cells are arranged in such a manner, that they are influenced by points at greater distances from each other, it is possible to employ a multiple tube, only then the distance between the electrodes B must be m'ade'accordingly greater'. The latter arrangement has the disadvantage, that for each of the selenium cells and for each of the electrodes B a separate lens must be provided.

In case one single t-ube is used, or a multiple tube, it is advisable, for producing greater contrasts in the received picture, to make the dimensions such, that the images of the luminous spots on the photo-sensitive film will, at highly illuminated selenium cells be larger than the distance between the neighbouring luminous points of the received picture. Then the images will more or less overlap with their edges, so that only very small dark points will remain between them. f y

Fig. 7 illustrates an indirectconnection in the case of an arrangement, with which a larger number of selenium cells s are employed in the transmitter combined to a panel. The individual cells are preferably connected successively by means of two commutators K and 7c into the circuit, of which commutators the one connects the cells inv rows, and the other, revolving at a higher speed, connects the cells ot' eachrow. In the receiver the electrodes A and B of the panel of fluorescent tubes are connected in a similar manner by means of two., synchronously revolving commutators K and c in the same series. The' commutator, revolving at the higher speed, of the transmitter may also, at the same time, serve as interruptor. Insteadof the panel of tubes one single multiple tube may be employed, which is moved in the plane of the panel, or witn which'a relative corresponding movement between the images of the luminous spots and the photo-sensitive film after one of the methods described hereinbefore with reference to the single tube is produced. Otherwise thev same applies here as has been said with ret?. erence to the Figures 5 and 6. Of course the transmitter according to Fig. 7,l may also`A be used in combination with the receiver according to Fig. 5 and vice versa the receiver according to Fig. 7` may-be used with the transmitter according to Fig. 5, provided an intermittent direct current or an alternating current is employed. l.

In all instances, where' several selenium cells or fluorescent tubesA are employed, it is ,also possible instead of the successive connection, to operate simultaneously, if several transmission lines are available, or, if only one such transmission line is available, alternating currents of ditl'erent frequencies are employed, each tube selecting its corresponding current by a correspondingly timed resonance circuit. y With suf-h fluorescent tubes the sensitivencss may be regulated, besides the regulation of the gas pressure which comes less into question for practical use by varying th(` step of the transformers, and by adding resistances or by superimposinga direct or an alternating voltage. By the latter it is possible to convert the alternating current supplied by the transformers into intermittent direct current, or, into an unsymmetric alternating current, the maximum value ot the positive momentary pressures ot which, may optionally be larger or smaller than the maximum of the negative 85 momentary pressures and vice versa. The regulation is preferably effected in such a manner, that when the selenium cell is not illuliiinated. the tube is but. slightly luminescent, and when the cell is strongly illuminated a luminous spot is produced, the maxi-.- mum diameter of which is about 1% times as great as the distance, between thel elec'- trodcs,'or the image of which is, at the same raie, larger than the distance between neighbouring points of thepicture received. Then the latter will, as regards appearance, fully correspond to a halt tone, in which, for practical reasons there are always still small dark points iiiithe highestlights, and small .100.

light points in the deepest shadows.

If the transmitting current is increasedby a quantitative -relay with variable current increasing factor, the regulation ot the sensitivcness of the fluorescent tube may 105 also be effected by varying the rate ot the relay, or by employing a variable shunt connected parallel to 'the relay.

I claim:

1. The combination in a glow lamp, of a plurality ot anodes and a plurality of cathodes, said anodes and cathodes being arranged in cooperative relation and disposed in coordinate rows. l

2. 'lhe combination in a glow lamp, ot a plurality ofrathodes each consisting of a metal strip, said cathodcs being arranged in parallel relation, and a plurality of anodes arranged in coordinate rows, said catl'iodes being adapted to cooperate with said anodes.

3. The combination in a glow lamp, of a pluralityv ot parallel cathodes each consisting of apertorated metal plate, 'and a plurality of rows of anodes each disposed opposite one of said cathodes and adapted to cooperate therewith.

4. The combination in a glow'lamp of a pair of spaced cooperating electrodes, one of said velectrodes being perforated, the other of said electrodes being disposed in lli such rela-tion to the perforated portion of the perforated electrode that a luminescent phenomenon occurs within the perforation.

5. The combination in a glow lamp of a perforated electrode element and a second electrode element disposed in spaced relation to said first electrode element, circuit connection terminals for said electrode elements, the arrangement being such that upon a suitable potential being appliedbetween said electrode elements, a luminous discharge is produced in and about the 4perforated portion of said iist electrode, said luminous discharge being visible from the l opposite the other MICHEL soHMrERER. 

